Polymerase chain reaction identification of Bacillus sporothermodurans from dairy sources

摘要

Aims: A new polymerase chain reaction (PCR) method for the identification of Bacillus sporothermodurans strains from sterilized or ultrahigh temperature-treated milk and milk products and from other non-milk sources and environments, including the dairy farm. Methods and Results: Two strains from raw milk and feed concentrate could be allocated to B. sporothermodurans based on 16S rDNA sequencing and DNA-DNA hybridization results. Two specific PCR primers were derived from the 16S rRNA gene of B. sporthermodurans. Conclusions: The PCR identification method was validated using a collection of B. sporothermodurans strains from different sources and on a large collection of dairy and non-dairy Bacillus spp. and other relevant taxa. Significance and Impact of the Study: This PCR method was used as a screening method for strains with very heat-resistant endospores, isolated at the dairy farm level after heat treatment for 30 min at 100 ℃. Seventeen strains isolated at the dairy farm were identified as B. sporothermodurans. They originated mainly from feed concentrate and also from soy, pulp and silage. The PCR identification method described here can, therefore, contribute to a better understanding of the route by which B. sporothermodurans contaminates raw and/or heat-treated milk.